It’s estimated that the heart, blood vessels, bones, and muscles deteriorate more than 10 times faster in space than by natural aging. This means to study the aging process, scientists don’t have to wait for their biological subjects to naturally mature on Earth—they can harness the accelerated health effects by running experiments on the International Space Station (ISS). Using over 300 biological samples, scientists catalogued a series of bodily differences in twin astronauts, including changes to the astronauts’ gene expressions, microbiomes, cognitive functions, and vascular systems.  Susan Bailey, a radiologist at Colorado State University involved in the studies, made the striking discovery that the telomeres of the twin who went into space lengthened. Telomeres typically shorten as we age, and how quickly telomeres shorten is an important marker of health.